Dear Lifehacker,
I know MP3 is the most popular audio format out there, but there are so many others—like AAC, FLAC, OGG and WMA—that I'm not really sure which one I should be using. What's the difference between them, and which one should I use to rip my music?

Sincerely,
Frustrated with Formats

Dear Frustrated,
You aren't alone in your confusion, but luckily, it's pretty simple once you understand it all. Here's a quick lowdown on the differences between each of these audio formats.

The Lossless Formats: WAV, AIFF, FLAC, Apple Lossless, and Others

We've talked about the difference between lossless and lossy before, but the short version is, there are two types of audio quality: lossless and lossy. Lossless music keeps all the audio quality of the original source—in most cases, CD—intact, while lossy music compresses the files for space savings (though at slightly diminished quality). Lossless files include:

WAV and AIFF: Both WAV and AIFF are uncompressed formats, which means they are exact copies of the original source audio. The two formats are essentially the same quality; they just store the data a bit differently. AIFF is made by Apple, so you may see it a bit more often in Apple products, but WAV is pretty much universal. However, since they're uncompressed, they take up a lot of unnecessary space. Unless you're editing the audio, you don't need to store the audio in these formats.

FLAC: The Free Lossless Audio Codec (FLAC) is the most popular lossless format, making it a good choice if you want to store your music in lossless. Unlike WAV and AIFF, it's been compressed, so it takes up a lot less space. However, it's still a lossless format, which means the audio quality is still the same as the original source, so it's much better for listening than WAV and AIFF. It's also free and open source, which is handy if you're into that sort of thing.

Apple Lossless: Also known as ALAC, Apple Lossless is similar to FLAC. It's a compressed lossless file, although it's made by Apple. Its compression isn't quite as efficient as FLAC, so your files may be a bit bigger, but it's fully supported by iTunes and iOS (while FLAC is not). Thus, you'd want to use this if you use iTunes and iOS as your primary music listening software.

APE: APE is a very highly compressed lossless file, meaning you'll get the most space savings. Its audio quality is the same as FLAC, ALAC, and other lossless files, but it isn't compatible with nearly as many players. They also work your processor harder to decode, since they're so highly compressed. Generally, I wouldn't recommend using this unless you're very starved for space and have a player that supports it.

The Lossy Formats: MP3, AAC, OGG, and More

For regular listening, it's more likely that you'll be using a lossy format. They save a ton of space, leaving you with more room for songs on your portable player, and—if they're
high enough bitrate—they'll be indistinguishable from the original source. Here are the formats you'll probably run into:

MP3: MPEG Audio Layer III, or MP3 for short, is the most common lossy format around. So much so that it's become synonymous with downloaded music. MP3 isn't the most efficient format of them all, but its definitely the most well-supported, making it our #1 choice for lossy audio. You really can't go wrong with MP3.

AAC: Advanced Audio Coding, also known as AAC, is similar to MP3, although it's a bit more efficient. That means that you can have files that take up less space, but with the same sound quality as MP3. And, with Apple's iTunes making AAC so popular, it's almost as widely compatible with MP3. I've only ever had one device that couldn't play AACs properly, and that was a few years ago, so it's pretty hard to go wrong with AAC either.

Ogg Vorbis: The Vorbis format, often known as Ogg Vorbis due to its use of the Ogg container, is a free and open source alternative to MP3 and AAC. Its main draw is that it isn't restricted by patents, but that doesn't affect you as a user—in fact, despite its open nature and similar quality, it's much less popular than MP3 and AAC, meaning fewer players are going to support it. As such, we don't really recommend it unless you feel very strongly about open source.

WMA: Windows Media Audio is Microsoft's own proprietary format, similar to MP3 or AAC. It doesn't really offer any advantages over the other formats, and it's also not as well supported. There's very little reason to rip your CDs into this format.

So Which Should You Use?

Now that you understand the difference between each format, what should you use for ripping or downloading music? In general, we recommend using MP3 or AAC. They're compatible with nearly every player out there, and both are indistinguishable from the original source if encoded at a high bitrate. Unless you have specific needs that suggest otherwise, MP3 and AAC are clear choices.

However, there is something to be said for ripping your music in a lossless format like FLAC. While you
probably won't notice higher quality, lossless is great for storing your music if you plan on converting it to other formats later on—since converting a lossy format to another lossy format (e.g., AAC to MP3) will produce files of noticeably lower quality. So, for archival purposes, we recommend FLAC. However, you can use any lossless format you want, since you can convert between lossless formats without changing the quality of the file.